Research Findings on Memory and Cognitive Impairment in ECT
Dr. Peter Como presented to the U.S. Food and Drug Administration Neurological Devices Panel examining the reclassification of electroconvulsive therapy (ECT) devices on January 27, 2011. This presentation comes from the public record of the meeting.
The FDA systematic review of the literature of cognitive adverse events [of ECT] included only randomized controlled trials as I mentioned. However, we did examine data from crossover designs if analyzable pre-crossover data were available. In addition, studies had to use standard psychometrically validated neuropsychologic tests.
The statistical comparisons that were examined included comparisons among various ECT treatment conditions, such as electrode placement, energy dose, frequency of treatment, waveform, and pulse. The comparisons also included ECT versus sham, ECT versus other treatments such as drug and medication placebo, and comparison of pre- and post-ECT changes in baseline cognitive test performance, although the pre- to post- ECT comparisons in themselves were non-randomized.
From this literature search, a total of 68 studies were identified which met these criteria.
This slide summarizes the findings of the published systematic reviews, meta-analyses, and practice guidelines. Overall, these sources indicate that there is evidence for impairment in orientation, anterograde and retrograde memory, and global cognitive function immediately after ECT that may last up to six months. Autobiographical memory is the most commonly reported memory impairment in these reviews. There is limited evidence to suggest that the effects of ECT on memory and cognitive function may not last more than six months.
A greater risk of memory or cognitive impairment is associated with sine wave compared to brief pulse ECT, bilateral and dominant hemisphere electrode placement, and the use of high energy dose ECT. This literature also suggests that raising the electrical stimulus above the individual seizure threshold increases the efficacy of ECT but at the expense of greater memory and cognitive impairment.
To continue, these summaries report that patient self- reported memory loss tends to be more persistent than the deficits that can be measured on formal neuropsychological testing. However, for those patients who do experience memory or cognitive impairment, they consider this to be a considerable source of distress for themselves and their families. The effects of ECT on cognitive function do not appear to differ among various psychiatric diagnoses such as schizophrenia and mania.
These summaries also suggest that factors other than the ECT treatment may impact cognitive function. These include individual variability, degree of improvement in depression, and the use of psychotropic medications at the same time as ECT.